A piezoelectric actuator described in Japanese Patent Application Publication Laid-Open No, 2012-156185 is a piezoelectric actuator used for an inkjet head. This piezoelectric actuator is provided with two piezoelectric layers, a common electrode and a plurality of individual electrodes. The two piezoelectric layers are laminated with each other, and continuously extend over a plurality of pressure chambers. The common electrode extends between the two piezoelectric layers substantially over the entire area thereof, and is held at the ground potential. The individual electrodes are disposed on parts, overlapping with the pressure chambers, of the upper surface of the upper piezoelectric layer, respectively, and a driving signal is input thereto. The parts of the upper piezoelectric layer sandwiched between the individual electrodes and the common electrode are polarized along the direction of the thickness. When the driving signal is input to an individual electrode to induce a potential difference between the individual electrode and the common electrode, the part of the piezoelectric layer sandwiched between these electrodes contracts in the direction of the surface, so that the part of the two piezoelectric layers overlapping with the pressure chamber is deformed so as to be convex to the pressure chamber side as a whole. Consequently the volume of the pressure chamber decreases to increase the pressure on the ink in the pressure chamber, so that the ink is jetted from the nozzle connecting with the pressure chamber.